docs: def save(self, commit=True):
          '''
          If a staff member is reporting substitute teaching for a second time, then we should update
          the list of occurrences for which they are a substitute on their existing EventStaffMember
          record, rather than creating a new record and creating database issues.
          '''
          existing_record = EventStaffMember.objects.filter(
              staffMember=self.cleaned_data.get('staffMember'),
              event=self.cleaned_data.get('event'),
              category=getConstant('general__eventStaffCategorySubstitute'),
              replacedStaffMember=self.cleaned_data.get('replacedStaffMember'),
          )
          if existing_record.exists():
              record = existing_record.first()
              for x in self.cleaned_data.get('occurrences'):
                  record.occurrences.add(x)
              record.save()
              return record
          else:
              return super(SubstituteReportingForm,self).save()